This invention relates to a combination switch and, in particular, to a combination switch which allows considerable savings in cost and occupies less space on attachment, as well as improving durability of the switch itself.
A motor vehicle typically implements an electrical system containing a wide range of components such as switches and motors designed to perform a variety of tasks. Switches are used for making and breaking circuits for operating electrical equipment, including some frequently used devices, on a vehicle. For example, a turn signal lamp is operated almost every time when the vehicle is going to turn left or right. Headlamps are necessary for driving in darkness. Windshield wipers are also frequently operated on running. Most of these electric devices are operated by means of manually turning or shifting a switch lever provided near the steering wheel and connected to the combination switch.
A conventional combination switch mainly consists of a fixed substrate and a movable substrate. The fixed substrate is mounted on the bottom of a housing while the movable substrate is slidably attached to the housing with being opposed to the fixed substrate. The movable substrate travels to a predetermined position on the fixed substrate by means of turning of shifting a switch lever operatively connected to the housing. The movable substrate comprises a plurality of switch contacts and a common contact whereas the fixed substrate comprises a plurality of output contacts (output throws). The output contacts on the fixed substrate are equal in number to the desired functions to be performed such as turn signal lamp flashing and headlamp lighting. In other words, one output contact on the fixed substrate is for operating a driver or a motor to perform one of these functions. Thus, each electric device is operated only when the output contact assigned therefor is connected to the switch contact or the common contact.
As mentioned above, a conventional combination switch requires three contacts for three functions and six contacts for six functions. Such one-to-one basis assignment is wasteful of contacts only to increase the number of components for rather complex and large-scale switch structure. It has thus been desired to reduce a size of a combination switch and thereby saving cost and space for mounting it. In addition, the material used for the contacts is metal such as phosphor bronze which tends to cause contact failure due to contamination on the contact surface. Dust is also one of the possible causes of the contact failure.